I've not been using Excel for a while. Has the AVERAGE function
changed in Excel 2003 from older versions?

If I have a set of data as follows in A1 to A4 as follows: 1, 2, 3,
"foo", then I expect AVERAGE(A1:A4) to complain bitterly that one of
those is, in fact, not a number (or rather, that it's not text that
can be converted to a number). Instead I get a result of 2.

Is there any way of getting Excel to use strong typing for these kind
of calculations, or do I have to rely on something ugly like
=IF(COUNT(A1:A4)=4,AVERAGE(A1:A4),"!!ERROR!!")

Cheers,

-- A.